MCM-68 is a single crystalline phase molecular sieve material which has a unique 3-dimensional channel structure comprising one 12-membered ring channel system and two 10-membered ring channel systems, in which the channels of each system extend perpendicular to the channels of the other systems and in which the 12-ring channels are generally straight and the 10-ring channels are tortuous (sinusoidal). The framework structure of MCM-68 has been assigned code MSE by the Structure Commission of the International Zeolite Association.
The composition and characterizing X-ray diffraction pattern of MCM-68 are disclosed in U.S. Pat. No. 6,049,018, which also describes the synthesis of the molecular sieve in the presence of a structure directing agent comprising the N,N,N′,N′-tetraethylbicyclo[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidinium dication. The entire contents of U.S. Pat. No. 6,049,018 are incorporated herein by reference.
U.S. Pat. No. 6,049,018 exemplifies the use of MCM-68 as a catalyst in aromatic alkylation and transalkylation reactions. In addition, U.S. Pat. No. 7,198,711 discloses that MCM-68 shows activity in the catalytic cracking of hydrocarbon feedstocks to produce an enhanced yield of butylenes and isobutene, with the MCM-68 either being the primary cracking catalyst or an additive component in conjunction with a conventional large pore cracking catalyst, such as zeolite Y.
The commercial development of MCM-68 has been hindered by the high cost of the N,N,N′,N′-tetraethylbicyclo[2.2.2]oct-7 -ene-2,3:5,6-dipyrrolidinium dication structure directing agent required in U.S. Pat. No. 6,049,018 for its synthesis and hence there has been significant interest in finding alternative, less expensive structure directing agents for the synthesis of MCM-68.
In U.S. Patent Application Publication No. 2009/0318696, it is stated that 1,1-dialkyl-4-cyclohexylpiperazin-1-ium cations and 1,1-diakl-4-alkylcyclohexylpiperazin-1-ium cations are effective as structure directing agents in the synthesis of MCM-68. U.S. Patent Application Publication No. 2009/0318696 describes the use of MCM-68 seeds in the synthesis of MCM-68.
UZM-35 can have some similarities in structure to MSE framework type materials in general, and to MCM-68 in particular. U.S. Patent Application Publication No. 2010/0081775 discloses a method for synthesizing UZM-35 using simpler, singly-charged cations. This reference, however, does note that UZM-35 has a unique x-ray diffraction pattern, different from MCM-68.
According to the present invention, it has now been found that relatively simple cations described herein can be effective as structure directing agents in the synthesis of MCM-68. Furthermore, it has been found that MCM-68 can be prepared with many of these cations in seeded preparations.